As an emerging technology, phase change materials attract more and more interest for their applications in manufacturing a new type of highly integrated, nonvolatile, memory devices: phase change random access memory (PRAM). Phase change random access memory (PRAM) devices are synthesized using materials that undergo a reversible phase change between crystalline and amorphous phases, that have distinctly different resistances. The most commonly used phase change materials are ternary compositions of chalcogenide of group 14 and group 15 elements, such as germanium-antimony-tellurium compounds, commonly abbreviated as GST.
One of the technical hurdles in designing a PRAM cell is that in order to overcome the heat dissipation during the switching of GST materials from crystalline to amorphous states at certain temperatures, a high level of reset current has to be applied. This heat dissipation can be greatly reduced by confining the GST material into contact plugs, that would reduce the reset current needed for the action. To build GST plugs on the substrate, atomic layer deposition (ALD) processes are used to produce films with high conformality and chemical composition uniformity.
Relevant prior art includes:
sang-Wook Kim, S. Sujith, Bun Yeoul Lee, Chem. Commun., 2006, pp 4811-4813.
Stephan Schulz, Martin Nieger, J. Organometallic Chem., 570, 1998, pp 275-278.
Byung Joon Choi, et al. Chem Mater. 2007, 19, pp 4387-4389; Byung Joon Choi, et al. J. Etectrochem. Soc., 154, pp H318-H324 (2007);
Ranyoung Kim, Hogi Kim, Soongil Yoon, Applied Phys. Letters, 89, pp 102-107 (2006).
Junghyun Lee, Sangjoon Choi, Changsoo Lee, Yoonho Kang, Daeil Kim, Applied Surface Science, 253 (2007) pp 3969-3976.
G. Becker, H. Freudenblum, O. Mundt, M. reti, M. Sachs, Synthetic Methods of Organometallic and Inorganic Chemistry, vol. 3, H. H. Karsch, New York, 1996, p.193.
Sladek, A., Schmidbaur, H., Chem. Ber. 1995, 128, pp 565-567.
U.S. patent applications:
US 2006/0049447 A1
US 2006/0039192 A1;
US 2006/0072370 A1; and
US 2006/0172083 A1.